Magnetic brake control



.Fuly 27, 19371 E. E. HEwn-T MAGNETIC BRAK CONTROL Filed oct. 24, 1935BNVENTOR ELUS l: HEWWT BY ,OM/ff df ATTORNEYv Patented July 27, 1937UNITED sr man einer RIAGNE'I'IC BRAKE. CONTROL Application October 24,1935, Serial No. 46,463

5 Claims.

This invention relates to magnetic brake control, and mo-re particularlyto the control of magnetic brakes employed on railway trains andtraction vehicles.

In certain types of brake equipments for railway trains and tractionvehicles it has been found desirable to employ a magnetic track brake inaddition to the usual fluid pressure brake. The magnetic track brake isappliedY by lowering the brake devices into engagement with the rail andenergizing the magnetizing windings associated with these devices toproduce a magnetic attraction betweenthe associated shoes and rails.

If the, Venergizing windings are maintained energized for anyappreciable length of time after the train or vehicle has been broughtto a stop, the heating produced may be so severe as to injure theinsulation of the windings and thus render the magnetic brakeinoperable. It is therefore desirable that the energizing windings bedeenergized when the train or vehicle has been brought to a stop.

Various means have heretofore been proposed for accomplishing thedeenergization of the track brake windings as the train or vehicle comesto a stop. In the present invention I contemplate an improved means foraccomplishing this function. According to my invention I provide a brakeequipment in which the track brake is not applied until fluid underpressure has been supplied to the brake cylinder of an associated fluidpressure brake portion of the equipment. In this manner an applicationof the track brake is effected during either a service or an emergencyapplication of the fluid pressure brakes, and without regard to thedegree of application so long as it is above a low predetermined value.

At any time fluid under pressure is released from the brake cylinderbelow `the lsaid predetermined value the track brake will be cut out ofaction, so that both the fluid pressure brake and.

the track brake are thus simultaneously released;

When the fluid pressure brake is applied, however, a switch device andan associated timing mechanism function to apply the track brake for apredetermined interval of time, which interval is preferably selected asone which is of suicient duration to bring the train or vehicle to astop under ordinary conditions, and one in which undue heating of thetrack brake windings will not result. f Y

A principal object of the present invention is to provide a novelarrangement of parts for carryingout the operation just referred to,which 'arrangement of parts may be readily adapted to trains andvehicles having already installed thereon a conventional type of fluidpressure brake.

A further object of the invention is to provide a novel magnetic brakecontrol which employs 'only devices which are known to be thoroughly 5reliable in operation.

Other objects and advantages of the invention will be more fullyunderstood from the following description, which is taken in connectionwith the single gure of the attached drawing, wherein 10 there is shownan embodiment of the invention adapted for a single vehicle.

Referring now to the drawing, the fluid pressure portion of the vehiclebrake equipment is represented by the brake cylinder lil to which 15fiuid under pressure may be supplied through pipe l i when effecting anapplication of the uid pressure brakes.

The magnetic brake portion of the equipment is represented by magneticbrake devices i2, each of 20 which has associated therewith a raisingcylinder i3, and magnet valve devices M for controlling the supply offluid under pressure to and its release from these raising cylinders.

For effecting an application of the track brake in response to fluidunder pressure supplied to the brake cylinder it, and for maintainingthe track brake applied for a predetermined interval of time, there areprovided pneumatic switch devices I5 and it, a timing magnet valvedevice I1 30 and a timing reservoir i8.

Considering now these devices more in detail, the magnetic brake devicesi2 may be of any of the conventional types employed, and each ispreferably provided with a yoke member 2li se- 35 cured thereto and to apiston rod 2l of a piston 22 disposed in a raising cylinder i3. Eachraising cylinder i3 is preferably secured to some part of the truckframe by means of a bracket 23, so that when iiuid under pressure issupplied to the raising cylinder i3 the piston Z2 will be actuatedupwardly and thus hold the track brake device suspended above the rail.When fluid under pressure is released from the raising cylinder i3, thetrack brake device l2 will drop by force of ,gravity 45 to engagementwith the rail.

The magnet valve device I4, which controls the supply of iiuid underpressure to and its release from the raising cylinder i3, is embodied ina casing provided with a supply valve 2li and a release valve 25. Aspring 26 urges the release valve 25 toward seated position and thesupply valve 2li toward unseated position. An electromagnet (not shown)in the upper part of the valve device casing functions when energized toactuate the supply valve 24 toward seated position and the release valve25 toward unseated position.

When the electromagnet is deenergized and the two valves 24 and 25 arein the positions shown in the drawing, a communication is establishedbetween a supply reservoir Z'I and each of the raising cylinders I3, sothat fluid under pressure may flow from the supply reservoir to theraising cylinders and thus hold the track brake devices I2 suspendedabove the rails. When the electromagnet is energized and the two valvesare actuated downwardly, this communication is cut off and each of theraising cylinders I3 is vented to the atmosphere past the unseatedrelease valve and by way of an exhaust port 26. The track devices arethus permitted to drop to engagement with the rail.

The two pneumatic switch devices I5 and I5 are essentially duplicates ofeach other. Each is embodied in a casing having a chamber in which isdisposed a piston 3|. The piston 3| is provided with a stem 32, andsecured to the upper end of the stern is an insulating member 33 whichcarries a bridging contact 34 adapted to bridge and connect together twostationary contacts 35.

A spring 36 urges the piston 3| downwardly, where in its downmostposition an annular rib 31 seals against a gasket 38. When the piston 3|is in its downmost position the bridging contact 34 is out of engagementwith the stationary contacts 35, as shown in the drawing.

When however fluid under pressure is supplied to the piston chamber 30the area of the piston Within the rib 37 only is initially exposed tothe pressure of the fluid, and when this pressure has risen to a valuesuch that the force on the piston breaks the seal between the rib 3'Iand gasket 38 the full face of the piston will be exposed and the pistonwill thus be actuated upwardly very quickly, thereby bringing bridgingcontact 34 into engagement with stationary contacts 35.

When fluid under pressure is released from the piston chamber 35, ordiminished below a predetermined degree, the spring 36 will actuate thepiston 3| downwardly and thus break the connection between the twocontacts 35.

The timing magnet valve device I'l is similar to the aforedescribedmagnet valve device I4, and is embodied in a casing provided with asupply valve 4|) and an application valve 4|. A spring 42 urges thevalve 4I toward seated position and the valve 4I) toward unseatedposition. An electromagnet (not shown) in the upper part of the valvedevice casing functions when energized to actuate the valve 43 towardseated position and the valve 4| toward unseated position.

When the two valves 43 and 4| are positioned as shown, that is when theelectromagnet is deenergized, a communication is established between thesupply reservoir 2l and the timing reservoir i8, so that the timingreservoir will be charged to supply reservoir pressure. When the valve4I] is seated and the valve 4| is unseated, the communication betweenthe supply and timing reservoirs is cut oi, and a new communication isestablished between the timing reservoir and the switch device l5, whichcommunication includes a pipe 43.

Connected between the pipe 43 and the atmosphere 'is a restriction inthe form of a choke When the timing reservoir I8 is thus connec-ted tothe piston chamber 30 in the switch device l5, uid under pressure willow from the timing reservoir to the chamber 30 and to the atmosphere byway of the choke 44. The pressure of the iluid supplied to the chamber33 will be suiflcient to actuate piston 3| upwardly so that bridgingcontact 34 bridges stationary contacts 35. But as will be more fullydescribed later, after a predetermined interval of time, the pressure inchamber 3i) will diminish to a value such that4 spring will returnpiston 3| to its lowermost position. The switch device |5 thus maintainsits contacts closed for a predetermined or chosen interval of time only.

The operation of this embodiment of my invention is as follows:

When it is desired to elect an application of the brakes, fluid underpressure is supplied to the pipe to a degree according to the desireddegree of application of the brakes. As the brake cylinder I isconnected directly to the pipe II, the uid pressure brake will beapplied to a degree corresponding to the degree of pressure in pipe I I.

Fluid under pressure supplied to pipe flows also to the piston chamber3U in the switch device i6. As before described, when this pressure hasreached a predetermined value, the piston 3| in the switch device I6will be actuated upwardly and its bridging Contact 34 will bridge andconnect together its stationary contacts 35. When this takes place, thetiming magnet valve device I7 will be energized from a source of currentsupply on the vehicle, such for example as a battery 45, through acircuit which includes beginning at the battery, conductor 46, contacts34 and 35 of switch device I5, conductors 41 and 4B, magnet valve deviceil, and conductors 49, 5U and 5I, which lead back to the battery 45.

Energization of the magnet valve device I'I will cause seating of valve43 and unseating of valve 4I, whereupon the timing reservoir I 8 will beconnected to the piston chamber 30 of the switch device I5 and to theatmosphere. This switch device will then actuate its bridging contact 34upwardly to bridge its stationary contacts 35. As will be observed fromthe drawing, a circuit will be established from the battery 45 to arelay 52, which circuit includes conductor 45, the contacts of switchdevice i5, conductors 4'I and 53, the contacts of switch device I5,conductor 54, the relay 52, and conductors 55, 5i] and 5| leading backto the battery 45.

Relay 52 will thus be energized and will close its contacts 56. Closingof these contacts establishes a circuit from the battery 45 to each 0fthe track brake devices I2 and to the magnet valve device I4, as will beapparent from the arrangement shown. The magnet valve device I4 willthus be energized to effect seating of its supply valve 24 and unseatingof its release valve 25. Fluid under pressure will then be released fromeach of the raising cylinders I3, and the track brake devices l2permitted to drop to engagement with the rail. When each track brakedevice has been energized, a braking effect will be produced on thetrack, and this braking effect will be concurrent with that produced bythe brake cylinder I0.

Current flowing to the track brake devices I2 flows through a resistancedevice 5'I which functions to limit the degree of current suppliedthereto.

Now since fluid supplied from the timing reservoir I8 to the pistonchamber 30 of switch device I5 flows to the atmosphere through the choke44,

it will be obvious that after a predetermined interval of time thepressure in piston chamber 30 will drop to a value such that spring 3Swill return piston 3l to its lowermost position, whereupon contact 34will disengage from contacts 35. When this takes place, the relay 52will be deenergized and thus open its contacts 5E. Opening of thesecontacts will of course deenergize both the brake devices i2 and themagnet valve device I 4. Fluid under pressure will then again besupplied to the raising cylinders i3 and the track brake devices will belifted from the rails.

The interval of time during which the track brake devices are energizedand applied to the rails is chosen as an interval of suicient durationto insure effective operation of the track brakes, and yet of insuicientduration to produce dangerous heating of the track brake devices.

If after lthe track brakes have been applied it is desired to releasethem before they wo-uld have been released due to functioning of thetiming means described, iluid under pressure may be released from thepipe il, thus causing opening of the contacts in switch device i6. Theoperator therefore may intermittently apply and release the track brakecoincidentally7 with intermittently applying and releasing the fluidpressure brake.

While I have illustrated my invention by means of one embodimentthereof, it is not my intention to be limited to the exact details ofthis embodiment, nor otherwise than by the spirit and scopeof theappended claims.

Having now described my invention, what I claim as new and desire tosecure by Letters Patent, is:

1. In a vehicle brake system, in combination, iluid pressure brakemeans, electrical brake means, iluid pressure operated switch meansadapted to be operated by fluid under pressure supplied to effect anapplication of said fluid pressure brake means, means operated upon anincrease in pressure for effecting an application of said electricalbrake means and operated upon a subsequent decrease in pressure foreffecting a release of said electrical brake means, and means operatedin response to operation of said fluid pressure operated switch meansfor eifectn ing a supply of fluid under pressure to said last mentionedmeans and for thereafter permitting said pressure to diminish below apredetermined degree in a chosen length of time.

2. In a vehicle brake system, in combination, a brake cylinder, a trackbrake, a first switch device adapted to be operated to a closed positionin response to pressure of fluid supplied to said brake cylinder, asecond switch device adapted to be operated by the supply of fluid underpressure thereto to effect an application of said track brake, meansoperated in response to operation of said first switch device to saidclosed pcsition for effecting a supply of fluid under pressure to saidsecond switch device, and means whereby the pressure of iluid suppliedto said second switch device is diminished in a predetermined length oftime to a value where said second switch device effects a release ofsaid track brake.

3. In a Vehicle brake system, in combination, a track brake device, arst set of normally open contacts, means rendered effective upon theclosing of said first set of contacts for effecting an application ofsaid track brake device, a second set of normally open contacts, fluidpressure operated means for closing said second set of contacts, andmeans responsive to closing of said second set of contacts for effectingclosing of said lirst set of contacts for a predetermined interval oftime.

4. In a vehicle brake system, in combination, a magnetic track brakedevice, a fluid pressure operated switch device having normally opencontacts for controlling a circuit through which current is supplied toeffect energization of said track brake device, a normally chargedreservoir, an electroresponsive valve device operable when energized toconnect said reservoir to said switch device to cause closing of saidcontacts, and means providing a restricted communication between saidswitch. device and the atmosphere, whereby the pressure of fluidsupplied to said switch device from said reservoir is slowly diminishedto a value insuflicient to maintain the contacts of switch deviceclosed.

5. In a Vehicle brake system, in combination, a brake cylinder, amagnetic track brake device, a battery, a relay controlling a powercircuit leading from said battery to said track brake device, a normallyopen relay circuit for energizing said relayY from said battery, aswitch device having normally open contacts in said relay circuit andoperable by brake cylinder pressure to close said contacts, and timingmeans controlled by said contacts and rendered effective only uponclosing of said contacts for subsequently opening said relay circuitafter a predetermined interval oi time.

ELLIS E. HEWITT.

